humongouspassenger is correct, it will make you sore if you're not careful. Friction and time are the culprits. I tied my cock and gun to my steering wheel one day and let it run while I drove for over an hour. Made quite the raw spot where my cording was, but boy did it feel awesome when I finally had to pull off to the side of the road so I wouldn't have to tell the cop, "No Sir! I wasn't texting. I was masturbating with my massage gun and when I came it was so intense I couldn't keep the car on the road! I'm so sorry, but I'll probably do it again, so just write me a ticket!"
Oh YEAH! I loved the precum dripping down the shaft during the work up to orgasm. What a wondrous river of cum. It just kept cumming and cumming. I love the messes my massage gun gives me!!
I love my massage gun, too. Cum comes out like a river! Warning: Your cock will be sore, so wait a couple days before using again! Seen here with his cock getting red!